Wiring a 3-Wire Dryer Outlet

By Dave Rongey - Summary:

Help with Electrical Wiring for a 30 amp 3-wire Dryer Outlet: Make sure that the white wire is wrapped with black or red electrical tape at both ends of the cable to identify it as being a hot wire and not a neutral wire.

Wiring a Dryer Outlet

Electrical Question: I need help wiring a 240volt outlet for a dryer.

Dryer Outlet Wiring Project

I have dedicated line with a double pole 30Amp breaker I want to use for a dryer.

The line was not in use and does not have an outlet, it is a 3 wire line, white,black and bare copper wire.

I bought a 3 prong 240Volt outlet.The instructions say to hook up the white wire to the L shaped prong and the two hot wires to the 45 degree prongs.

I tested the lines with a multimeter and the voltage between the white and bare copper wire is 120v, 120v between the black and cooper and 240v between the white and black.

The two hot wires are the white and black and the bare copper wire is the neutral?

Should the outlet be hooked up with the copper wire to the L shaped prong and the white and black to the 45 degree hot prongs?

This electrical question came from: Joe, a Homeowner from Texas.

Dave’s Reply:
Thanks for your electrical question Joe.

How to Wire a 30 amp 3Wire Dryer Outlet

Application: 240Volt Dryer Outlet Wiring.
Skill Level: Intermediate to Advanced – Best installed by a Licensed Electrician.
Tools Required: Basic Electricians Pouch Hand Tools and a Voltage Tester.
Estimated Time: Depends on personal level of electrical experience, ability to work with tools and the available access to the dryer cord electrical connection box.
Precaution: Identify the dryer circuit, turn it OFF and Tag it with a Note before working with the dryer outlet or cord wiring.

Wiring Connection for a 30amp 3wire Dryer Outlet

Yes Joe, that’s right, the L-shaped prong is for the ground wire.

In an example like this the L shaped prong is the ground wire connection for the bare copper wire.

Make sure that the white wire is wrapped with black or red electrical tape at both ends of the cable to identify it as being a hot wire and not a neutral wire.

Hi Hilton,
Please check with the owners manual for the new dryer to see if it may be wired with the three wire system. Some new dryers require a dedicated neutral, which in that case would require a 4-wire circuit.
I hope this helps,
Dave

I have a 3 prong dryer outlet but there are 4 wires red black green white the red and black on the sides and green connected to the bottom but the white is not connected, so will that not make the dryer work or is that in case I need to switch to a 4 prong.

Hi Rich,
Depending on the age of the home, some dryer circuits are wired with a 4wire circuit, and it could be that the last dryer had the 3wire hookup and the outlet was changed to be a 3wire outlet. This can be verified by inspecting the dryer outlet wiring, and if that is the case then it would be best to replace the 3wire outlet with a 4wire outlet and make sure to connect all 4 wires accordingly. Some newer dryers will allow converting from a 4wire cord to a 3wire cord, but that needs to be verified with the information about the exact dryer that you have. Please refer to the links in the above information that will lead you to the dryer wiring diagrams.
I hope this helps.
Dave

I have 2 electric dryers both are 3wire hook up. One dryer has a black, neutral, ground, and red wire. The other has yellow/white, green and red wire. I want to hook up the one that has yellow/white green/red. Can put the black wire in place of the yellow?
Thank you.

Hi John,
I believe what you are describing are the wire colors that are inside the dryer which are found connected to the wiring terminals. Typically the 3-wire power connections of the 240 volt lines are connected to the two outside terminals and the ground is connected to the center terminal. However you should verify this by closely looking at the wiring diagram that should be on the dryer, or on the inside of the cover plate of the terminal connection area, or check with the installation manual that came with the dryers. The installation manual will provide guidance for the correct connections for your specific dryers and will indicate if your may or may not use a 3-wire connection. This is important because many new dryers will require a 4-wire connection where a separate neutral wire is required.
Dave

Electrical Wiring and Electrical Repairs

Unless otherwise posted, please refer to the following Guidelines for Electrical Projects:
Skill Level:
Intermediate to Advanced - Electrical Repairs and Circuit Wiring is Best Performed by a Certified Electrician or Licensed Electrical Contractor.
Electrical Tools Required:
Basic Electricians Pouch of Hand Tools, a Voltage Tester and a Multi Meter.
Estimated Time:
Depends on personal level experience, ability to work with tools, work with electrical wiring, and the available access to the project area.
Precaution:
Identify the project circuit, turn it OFF and Tag it with a Note before working with the wiring.
Important:
Modifying existing electrical circuits or installing additional electrical wiring should be done according to local and National Electrical Codes, with a permit and be inspected.